22 research outputs found
Attraction properties of the Ginzburg-Landau manifold
No full textWe consider solutions of weakly unstable PDE on an unbounded spatial domain. It has been shown earlier by the first author that the set of modulated solutions (called "Ginzburg-Landau manifold") is attracting. We seek to understand "how big" is the domain of attraction. Starting with general initial conditions of order " for the Fourier-transformed version of the given PDE we find that on the time-scale T " ; 2 (that is long in the terms of the original "physical" time t, but shorter than the natural time for the Ginzburg-Landau) the corresponding solutions evolve to the scaling of the clustered modes-distribution peaked at the integer multiples of the critical wave number, with the amplitudes sensitively dependent on such that for arbitrary close to zero after the time T " ; 2 solutions get on the Ginzburg-Landau manifold
MM-wave Patch Antenna with Embedded Photoconductive Elements for 1-bit Phase Shifting
No full textThe paper presents a development approach for mm-wave patch antenna with 1-bit (0/180 degrees) phase shifting. The proposed design employs a stacked patches structure, where the lower patch is excited symmetrically from an embedded single-pole double-throw switch. The switch is based on controllable photoconductive elements, where each element represents a high-resistivity silicon piece, which conductivity is modulated by a light source. Measured results demonstrate achievable (23-26) GHz -10-dB matching bandwidth and radiated field phase switching of (170-173)degrees. The approach can find its applications in beam steering antenna arrays and switchable monopulse antennas
Method for Phased Antenna Array Autofocusing with Amplitude-only Measurements
No full textThe paper presents an approach for fast antenna array autofocusing on a receiver position. The autofocusing procedure provides the maximum output power at receiver\u27s output. At the same time, the receiver is only capable of amplitude measurements. The crucial idea of the suggested method is employment of all phased antenna array\u27s radiators simultaneously, which makes the method suitable for arrays without amplitude control inside channels. We propose the representation of sought-for channel propagation vector as a linear combination of Hadamard matrix rows, whose complex coefficients are found from the suggested measurement procedure. The approach can be useful for different applications such as long-distance wireless power transmission, finding the channel state information matrix in communication systems and for antenna arrays calibration problems
Sub-THz U-Slot Coupled Stacked-Patch Radiating Elements for Dual-Polarized MIMO Array Antennas
No full textSeveral sub-THz (D-band, 136-148 GHz) dual-polarized array elements (unit cells, UCs) implemented in a multi-layer PCB technology are investigated in the infinite array environment. The elements are stacked-patch antennas with unbalanced aperture-coupled feeds (U-slots), having a slant 45 deg. polarization. We demonstrate that a baseline half-wavelength cavity-backed UC is capable of achieving ≤ 3.7 dB scan loss in the 60 deg. conical scan range and (132-149) GHz bandwidth. For the increased UC size, however, active polarization channel isolation drastically degrades and the element experiences scan blindness. To address this problem, a UC modification is introduced that suggests using a single-row mushroom-type electromagnetic band-gap structure along the UC sidewalls. Simulated results evidence the realized UC decoupling and elimination of the scan-blindness anomalies in the full visible scan range, with scan loss ≤ 4.2 dB in the 55 deg. conical scan range and (136-148) GHz bandwidth
The method of calculation and priority when crossing controlled intersection in the interval shifts permitting traffic light signal prohibiting
No full textThe article shows the need to establish the values of the deceleration value of the vehicle, which drivers must carry out speed reduction in the pace "without resorting to emergency braking." The definition of "emergency braking", not in the normative legal acts of the Russian Federation, and the deceleration of vehicles when you apply a driver braking temp without resorting to emergency." The example of calculation of the technical capabilities to make a stop in place, regulated by the Rules of the road, at the moment when the yellow traffic light when applying the emergency brake and brake on the pace, "without resorting to emergency.
Low-loss K-band Photoconductive Switches in SIW Technology
No full textA design approach for mmWave switches in substrate integrated waveguide (SIW) technology is demonstrated. The switch is based on a photoconductive element (PE) which represents a piece of an intrinsic silicon wafer with light modulated conductivity. Using both dielectric (high-resistivity) and conductive states of the PE, we can design a low-loss mmWave switching element. Owing to the light actuation, the control circuitry of the photoconductive switch (PS) is electrically separated from the high-frequency elements of the device. This solves the bottleneck of conventional mmWave switches based on PIN diodes, MOSFETs, MEMS, etc., which are bulky and lossy due to decoupling filters and matching elements of control and biasing circuits. The proposed approach is generic and can be applied to many mmWave applications within 10\ua0—\ua0100\ua0GHz such as 5G, WiGig, automotive radars, and others
